The default/standard “Flagged” perspective in Omnifocus 2 for Mac is to group by context. In Omnifocus 2 for iPhone, it’s not grouped at all, and I’m not sure what the sort is. Is there a way to change the default “flagged” perspective (orange flag icon on home screen) in OmniFocus for iPhone to work as on the Mac?
I don’t think the built-in perspectives can be changed, unfortunately.
My only suggestion would be to create a new perspective that does what you want and sync that to the iPhone.